This invention relates to indwelling devices for passing fluids into or out of the body, especially such devices which include a stabilizing cuff, and more particularly to a device of the type described which provides a visual warning when damage occurs to the stabilizing cuff.
Endotracheal tubes and catheters are well known devices that help facilitate passage of fluid from or into the body. Although the following description is directed to endotracheal tubes, the problems described are also applicable to catheters and any other similar devices employing inflatable or expandible stabilizing cuffs.
Endotracheal tubes are usually placed in a patient's trachea during anesthesia to direct oxygen and anesthetic gas into the lungs, and to maintain a respiratory flow path during a surgical procedure.
Most endotracheal tubes include an inflatable or expandible stabilizing cuff located near a distal end of the tube. The cuff is preferably in an uninflated condition prior to installation of the tube in a body passage such as the trachea. After the tube is disposed in the trachea, the cuff is expanded with fluid such as air or saline to lodge the cuff within the passage and thereby fix the location of the endotracheal tube.
The inflation cuff can be formed of a thin sheath of flexible, expandable, biocompatible material such as silicone rubber or PVC plastic attached to the periphery of the tube to form a leak tight chamber. The typical endotracheal tube also includes an inflation lumen communicable with the cuff and noncommunicable with the main air flow passage of the tube. The inflation lumen is adapted to communicate with a supply of fluid for inflating the cuff to its expanded condition.
In many surgical procedures, especially where there is a need to perform a remote cutting operation, a laser is used to effect some portion of the tissue cutting or tissue removal. Occasionally the laser beam is inadvertently directed toward the endotracheal tube and strikes the inflation cuff. A piercing of the cuff by the laser can cause evacuation of the inflation fluid and destabilization of the cuff.
If an inflatable cuff is filled with a gas such as air, a laser strike at the cuff is likely to result in immediate evacuation of the captive air and possible ignition or smoldering of the cuff material. Oftentimes a laser strike at a cuff occurs without warning and in some instances the damage is not immediately recognized. Thus a delay in recognizing such problem inevitably results in a delayed remedy.
Since the inflation cuff is desirably formed of relatively thin expandable material, it is not feasible to incorporate laser resistant properties therein, which could adversely affect the expandability of the cuff.
One alternative to air inflation is to fill the cuff with a liquid such as saline. A saline filled cuff includes safety features that are especially desirable in a surgical environment where lasers are used. For example, if a laser strikes a saline filled cuff, the saline can extinguish or prevent laser induced ignition or smoldering of the cuff. Furthermore, an inflation cuff filled with saline can diffract a laser beam that passes through the cuff, thereby reducing the energy of the laser beam.
A further advantage of a liquid filled cuff, rather than a gas filled cuff, is that the evacuation of a liquid filled cuff, due to a laser strike, is usually slower than that of a gas filled cuff. Thus an operating team has more time to identify and remedy the problems that result from a laser strike to a cuff.
In many instances, one or more layers of cotton material, also known as neuro-sponge, are wetted and packed around the endotracheal tube distally of the inflation cuff for cooling purposes. However, such packing can camouflage a laser strike to the cuff and delay recognition of the damage caused by the laser strike.
To facilitate recognition of a pierced or otherwise damaged inflation cuff due to such inadvertencies as a laser strike, it has been suggested that methylene blue dye be added to the inflation liquid for the cuff. The methylene blue dye is understood to be an abnormal color at a surgical site and is easily recognized against body tissue, and especially against white cotton packing material. Thus methylene blue dye which issues from a cuff following a laser strike is an effective warning signal to an operating team to take whatever corrective action is necessary to remedy damage to the inflation cuff. In addition, the methylene blue dye is a medium with higher diffracting properties than saline.
Methylene blue dye is usually applied to an endotracheal cuff by initially drawing the liquid dye into an external syringe and then infusing the dye from the syringe into the cuff. Unfortunately, methylene blue dye, when supplied externally to the endotracheal tube during the intubation process, is not convenient to use since it is a staining material, and the utmost precautions must be taken to avoid leakage of such dye during intubation. Should methylene blue dye inadvertently leak and stain a receiving material around the patient during intubation, the utility of the dye would be compromised because such leakage stain might be confused with the methylene blue dye that is intended to be evacuated in the event of a laser strike at the inflation cuff.
A further problem is that additional time beyond that required for normal intubation must be taken to mix an external supply of saline with methylene blue dye and administer the dye to the endotracheal tube using whatever special precautions are necessary to assure that there is no leakage of methylene blue dye during intubation. When time is of the essence, as is usually the case in an operating room, it is not feasible to spend extra time to mix an external source of methylene blue dye with the inflation fluid immediately prior to intubation.
It is thus desirable to provide an endotracheal tube or a catheter which is capable of yielding a visual warning of inflation cuff damage without the need for an external injection source of a leak detection material during the intubation process.